As power grids become more and more complex, system operation security has become a big concern. Voltage security assessment is a powerful way for measuring system operation security because such assessment can provide information about how certain contingency would affect the whole power system. Base on the assessment, the system operators can evaluate system security and determine feasible control actions.
Several conventional techniques have been developed to perform voltage security assessment in a power system. For example, traditional operational planning studies may be applied with transmission line tripping and load forecast. These studies, however, are time consuming and are only suitable for off-line analysis. In another conventional technique, P-V curves and V-Q curves are used in voltage stability analysis. Information, such as critical limits, operation region, etc, can be readily identified in these curves. In a further example, dynamic and/or static modal analysis may be performed for voltage security assessment. Dynamic analysis is similar to transient stability analysis while static analysis is based on eigenvalue analysis or singular value decomposition of a system power flow Jacobian matrix. A stability degree can be identified by computing the eigenvalues and eigenvectors of the reduced Jacobian matrix. Bus, generator, branch participation factors can also be attained to evaluate the contribution of each component.
On-line voltage security assessment has attracted a great deal of interest lately. Many techniques have been proposed. However, most of these techniques utilize at least some of the foregoing techniques for assessment. Other techniques have also been developed to perform the same function, such as neural network method, fuzzy-logic method, adaptive bounding method, and case-based reasoning approach. However, these techniques are complex and computationally demanding. Accordingly, there is a need for systems and methods for efficiently and cost-effectively assess operation security in a power system.